{"title":"Generic Stability Impedance Criterion for the Parallel Inverters System","authors":"Xin Zhang, Jinsong He, Chung, Shu-hung Henry","doi":"10.1109/SPEC.2018.8635992","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635992","url":null,"abstract":"Parallel inverters are always utilized in renewable energy systems to transfer the power from different renewable resources to the grid. However, the parallel inverters may suffer instability problem, i.e., even though each inverter is stable individually, the paralleled inverters may be unstable due to the interaction among these inverters or cables. Though a lot of existing stability impedance criteria have already been proposed to assess the stability of the paralleled inverters, they are all targeting specific systems with special assumptions, such as supposing all the inverter parameters are the same, ignore the cable’s impedance or treat all the cables as short cables, etc. In this paper, a generic stability impedance criterion has been proposed without any assumptions. Hence, this proposed criterion can evaluate the stability of any types of parallel inverters with different inverter parameters and long/short cables. The detailed derivation of the proposed criterion has also been presented. Finally, the effectiveness of this criterion has been validated by a 5 kW parallel inverters system including three totally different inverters & cables.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131773060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jinghua Zhou, Rong Zhang, Xinlei Zhang, Jiewei Wu, Weichao Huang
{"title":"A Compound Control Strategy for Inverter Output Voltage in Micro-grid System","authors":"Jinghua Zhou, Rong Zhang, Xinlei Zhang, Jiewei Wu, Weichao Huang","doi":"10.1109/SPEC.2018.8635643","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635643","url":null,"abstract":"For poor inverter output voltage quality caused by operation of asymmetric load and nonlinear load in the micro-grid system, a compound control strategy for inverter output voltage was proposed; in this paper, based on positive sequence rotating coordinate system, Proportion Integrator (PI)+ Vector Proportion Integrator (VPI) controller was used to control fundamental voltage and unbalanced voltage. And based on two-phase static coordinate system, VPI controller was used to control harmonic voltage to finally realize voltage quality governance. In addition, DC/AC + z-type grounding transformer topology was adopted to solve supporting problem of single-phase load by a three-phase three-wire inverter. Finally, a 2.5MW converter device was established to carry out an experimental study based on TMS320F28377D controller. The experimental result verified effectiveness of the proposed control strategy. At present, this device has been applied to flexible substation system in Aliyun data center located in Zhangbei County, Zhangjiakou City, China.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129667515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhancing the Natural Voltage Balancing Capability of Neutral-Point-Clamped Converters under Carrier-Based Pulsewidth Modulation","authors":"N. Beniwal, J. Pou, C. Townsend, S. Ceballos","doi":"10.1109/SPEC.2018.8635951","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635951","url":null,"abstract":"In this paper, a new modulation technique is presented which aims to enhance the natural voltage balancing capability of neutral-point-clamped converters. The traditional carrier-based pulsewidth modulation technique with zero-sequence injection faces some drawbacks, namely, its inability to balance initial capacitor voltage imbalances quickly and the divergence of the capacitor voltages in the presence of nonlinear loads with even harmonics. This paper aims to find a trade-off between voltage balance performance and switching losses by reducing the difference between the average capacitor voltages without incorporating any external circuitry. A reference neutral-point (NP) current is generated using the average difference between the capacitor voltages. Depending on the reference NP current and predicted NP current, appropriate duty cycles are applied to switch the three phases. These duty cycles are directly linked to the voltage unbalance between the capacitor voltages and thus provides the necessary 'push' to mitigate deviations in natural balancing characteristics. To validate the proposed modulation technique, simulation results are presented for linear loads as well as for nonlinear loads with even harmonics.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130942201","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Jeon, G. Farivar, C. Townsend, Joung-Hu Park, J. Pou
{"title":"Capacitor Voltage Shaper for Cascaded H-Bridge StatCom","authors":"Y. Jeon, G. Farivar, C. Townsend, Joung-Hu Park, J. Pou","doi":"10.1109/SPEC.2018.8635915","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635915","url":null,"abstract":"In this paper, an active shaping method of the capacitor voltage for a cascaded H-bridge (CHB) Iow-capacitance static synchronous compensator (LC-StatCom) is introduced. The traditional LC-StatCom is able to operate with large capacitor voltage ripples when it is operating with rated current. However, as the current is reduced below rated current, voltage ripple on the capacitors decreases. Decreasing the current therefore removes the advantages of the LC-StatCom such as better current quality and reduced switching losses. The active shaping method aims to keep consistent large voltage ripple on the capacitor using a simple boost converter cell to inject an appropriate auxiliary capacitor current. Simulation results are provided to confirm the performance of the proposed CHB-StatCom system.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125134360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Revisiting Two-Port Network Analysis for Wireless Power Transfer (WPT) Systems","authors":"P. Jayathurathnage, M. Vilathgamuwa, C. Simovski","doi":"10.1109/SPEC.2018.8635846","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635846","url":null,"abstract":"This paper discusses the applicability of the two- port network model for the analysis of wireless power transfer (WPT) systems. The two-port network model has been extensively used to analyze microwave circuits, and identical principles have been applied to WPT. The standard gain parameters defined for the two-port networks are critically analyzed with regards to WPT systems. The usefulness and the practical limitations of the gain parameters are highlighted. In addition to power transfer efficiency (PTE), an alternative gain parameter, square voltage gain is defined to estimate the power transfer capability of the WPT system. The proposed performance indices are then computed in terms of generalized two-port network parameters along with a generalized optimization methodology. A case study is presented for the optimization of a WPT system with a repeater.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116770207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Design Procedure for a Digital Proportional-Resonant Current Controller in a Grid Connected Inverter","authors":"T. Busarello, J. Pomilio, Marcelo Simoes","doi":"10.1109/SPEC.2018.8636052","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8636052","url":null,"abstract":"This paper presents a design procedure for a digital Proportional-Resonant (PR) current controller in a Grid Connected Inverter (GCI). The procedure describes a systematic list of how to compute the proportional and resonant gains as well as the coefficients for the digital resonant path. The main contribution of the design procedure is to facilitate and to support researchers who are designing GCI with current control strategies in a digital environment. The paper also presents a frequency domain analysis of a designed digital PR controller. The fictitious w-domain is used in such analysis. A case study shows the efficacy of GCI with a digital PR current controller designed based on the proposed procedure. Later, the paper discusses that the proposed procedure is valid also for digital PR controller with multiple resonant paths.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130296762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Comparative Study of Performance for Different Winding Connections of Dual-channel Switched Reluctance Machine Using Frozen Permeability","authors":"X. Cui, Jianbo Sun, C. Gu","doi":"10.1109/SPEC.2018.8635851","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635851","url":null,"abstract":"Inductance characteristics play an important role in the output torque of the switched reluctance motor (SRM) whereas the windings connection form affects the mutual coupling between phases. According to the magnetic polarity models, dual-channel switched reluctance machine (DCSRM) with NNNSSSNNNSSS winding polarity is defined as DCSRMI, DCSRM with NSNSNSNSNSNS is defined as DCSRM2 and DCSRM with NNSSNNSSNNSS is defined as DCSRM3. Previous papers show that DCSRMs with different winding connections can offer different average torque, copper loss, iron loss and efficiency, but the work that different winding connections of DCSRMs running with channel fault is rarely carried out. This paper presents comparative studies of dynamic performance and magnetic characteristics of DCSRMs running with channel fault whereas only the winding connection type that differs. The frozen permeability method is adopted to compute static inductance and torque characteristics and to analyze the magnetic characteristics of the different winding connection models. The results show that the connection type of DCSRM3 can obviously enhance the average torque and minimize the torque ripple under the condition of channel fault. However the iron loss of DCSRM3 is highest among the three types under dual-channel excitation condition, which lowers the overall efficiency. By simulation analyses, a novel four-phase 16/12-poles fault-tolerant DCSRM called even-phase fault tolerance has been proposed. No matter in dual-channel excitation nor in single-channel excitation operation conditions, the performance of this even-phase DCSRM can be the best.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130909936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Impact of Mechanical Power Variation on Transient Stability of DFIG-based Wind Turbine","authors":"Wangqianyun Tang, Jiabing Hu, Rui Zhang","doi":"10.1109/SPEC.2018.8635978","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635978","url":null,"abstract":"The input mechanical power affects the transient stability by changing the transient energy of the power system. The mechanical power characteristics of doubly fed induction generator (DFIG)-based wind turbines (WTs) are more complex and the variation ranges are wider when compared with those of synchronous generators (SGs’) owing to the different energy conversion mechanisms, which leads the transient stability of DFIG-based WT more diverse. This paper systematically analyzes the impact of the mechanical power variation on the transient stability of DFIG-based WT. Firstly, the analytical model considering the mechanical power is presented. In comparison with SG, the characteristics of mechanical power of the DFIG-based WT are summed up. Then, based on the model, the transient stability of a single DFIG-based WT-connected system is theoretically analyzed. The instability mechanism and phenomena are found to be variable in different wind speeds. Finally, the impacts of the summarized factors of mechanical power on transient stability of DFIG-based WT are discussed, including the wind conditions, aerodynamics and pitch controls.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130973740","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Isolated Three-Port DC-DC Converter with Low-Voltage DC Bus for DC Microgrids","authors":"Panbao Wang, Xiaochen Zhang, Sibao Ding, Wei Wang, Dianguo Xu","doi":"10.1109/SPEC.2018.8636080","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8636080","url":null,"abstract":"The application of multi-port DC converters in DC microgrids (MGs) can effectively improve the integration and reliability of the system. This paper proposes an isolated three-port converter (TPC) with common low-voltage DC bus which is suitable for DC MGs. The proposed TPC is able to achieve bidirectional power transmission between the high-voltage side and the low-voltage side through the dual active bridge (DAB), while the power conversion of the low-voltage side is consisted of buck-boost converters. The number of power devices of the TPC is reduced by multiplex use of the power devices in the DAB. Meanwhile, interleaved structure is employed to reduce the current ripple at one port on low-voltage side. This paper analyzes the equivalent circuit model of the proposed TPC, then typical operating modes and key waveforms of the converter are presented. The phase-shifting control with duty-cycle adjustment method is adopted to realize bidirectional power transmission among the three ports. Finally, the power transmission characteristics of the TPC are verified by simulation and experimental studies, and the effectiveness of the proposed scheme is verified accordingly.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125963874","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wesley Poh Qi Tong, B. M. Muhammad Ramadan, T. Logenthiran, R. T. Naayagi, W. L. Woo, V. Phan
{"title":"High-Performance CLL Resonant Multi-Channel LED Driver for Lighting Application","authors":"Wesley Poh Qi Tong, B. M. Muhammad Ramadan, T. Logenthiran, R. T. Naayagi, W. L. Woo, V. Phan","doi":"10.1109/SPEC.2018.8635959","DOIUrl":"https://doi.org/10.1109/SPEC.2018.8635959","url":null,"abstract":"This paper presents a multi-channel, current-balancing coordinated light-emitting diode (LED) driver that employs a primary buck converter and a secondary two-stage CLL resonant-based inverter. The proposed LED driver is engineered with a switch-mode voltage regulator that maintains high power dissipation, controls current-carrying capacities respecting to load using half-bridge inverter coupled to a CLL resonant tank, and pose operating cycle uniformity at multiple current source outputs by cascaded balance capacitor-based transformers with voltage-doubler architectures. Conjointly, utilization of high switching frequency (282.7kHz) is endorsed to curtail current ripple deviations and stimulate balanced current distribution based on load capacities. Using PSIM simulation environment, the proposed multi-channel LED driver is evaluated to view its performance against dynamic installation of multi-stringed LEDs connected at variegated capacities. Succeedingly, development of a hardware prototype is annexed. The acquired simulation and hardware tests’ results have validated optimal coordination of current distributions for unbalanced loads (LEDs) across multiple channels.","PeriodicalId":335893,"journal":{"name":"2018 IEEE 4th Southern Power Electronics Conference (SPEC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130065294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}